The objective of this project is to study the specificity of functions and of receptors of thymus derived cytotoxic lymphocytes (T killer cells). The ultimate aim of these experiments will be to isolate and to biochemically characterize the antigen receptor of T killer cells. For our experiments we will use two kinds of permanent cell lines of T killer cells: One is dependent on spleen cells for proliferation and the other is dependent on conditioned medium. First, we will clone both types of cell lines then characterize and compare their specificity of functions i.e. cell proliferation, cytotoxic activity and allogeneic effect. In particular, we will map the H-2 region genes which code for the antigens recognized by these cells during cell proliferation, cytotoxicity and allogeneic effect. Second, we will search for receptors released by these cell lines into the tissue culture supernatant using the triggering of bone marrow derived lymphocytes for antibody synthesis as assay. Third, we will construct hybridomas which produce antibody to cell surface antigens of these T killer cell lines. A number of serological and biochemical procedures will be used to explore the specificity of these antibodies in order to find those which bind to the T killer cell receptor. Once a receptor specific antibody is found the T killer cell receptor could be isolated.